A Multi-wavelength Survey of AGN in Massive Clusters: AGN Distribution and Host Galaxy Properties

TL;DR

This study explores how the environment in massive galaxy clusters influences the distribution and properties of AGN and their host galaxies, revealing environmental effects on AGN activity and host galaxy colors.

Contribution

It provides a multi-wavelength analysis of AGN distribution and host galaxy properties in clusters, highlighting environmental impacts on AGN fueling and galaxy evolution.

Findings

AGN distribution varies across clusters and differs from normal galaxies.

Many AGN hosts are in the 'green valley' between red and blue galaxies.

Disturbed clusters show more pronounced AGN host color distributions.

Abstract

We investigate the effect of environment on the presence and fuelling of Active Galactic Nuclei (AGN) by identifying galaxies hosting AGN in massive galaxy clusters and the fields around them. We have identified AGN candidates via optical variability (178), X-ray emission (74), and mid-IR SEDs (64) in multi- wavelength surveys covering regions centered on 12 galaxy clusters at redshifts 0.5 < z < 0.9. In this paper, we present the radial distribution of AGN in clusters to examine how local environment affects the presence of an AGN and its host galaxy. While distributions vary from cluster to cluster, we find that the radial distribution of AGN generally differs from that of normal galaxies. AGN host galaxies also show a different colour distribution than normal galaxies, with many AGN hosts displaying galaxy colours in the "green valley" between the red sequence and blue star-forming normal galaxies. This result is similar to those found in field galaxy studies. The colour distribution of AGN hosts is more pronounced in disturbed clusters where minor mergers, galaxy harassment, and interactions with cluster substructure may continue to prompt star-formation in the hosts. However, we find no relationship between host galaxy colour and cluster radius among AGN hosts. This may indicate that processes related to the accreting supermassive black hole have a greater impact on the star-forming properties of the host galaxy than the intracluster medium and/or local galaxy environment.